Micelles catalytic properties

J. Aguado, D. P. Serrano, R. van Grieken, J. M. Escola, and E. Garagorri, Catalytic properties of micelle templated microporous and mesoporous materials for the conversion of low-density polyethylene. Stud. Surf Sci. Catal, 135, 3915-3922 (2001). 

Any survey of the literature dealing with studies of the catalytic properties of solutions containing polymers or micelles will quickly show that the most powerful motivation for such work was provided by the hope that such systems would exhibit some analogy to the behavior of enzymes. It seems, therefore, appropriate to touch on a few characteristics of enzymic catalysis before considering the subject of this review. 

Many hydrolytic studies have been reported utilizing both micellar and synthetic pol3nneric systems. Cordes (7 ) and co-workers, and Ocubo and Ise ( ) have reported on systems which incorporate both the novel features of micelles and polyelectrolytes, i.e., catalyst systems which have binding sites available for both strong hydrophobic and electrostatic interaction with suitable substrates. Such hydrophobic polyelectrolyte systems have been prepared and have been termed "polysoaps" (9,10). The catalytic properties of these polysoaps has remained largely unexplored. 

This effect has been studied in our group by Kenichi Morigaki in his dissertation. He utilized the hydrophobic tripeptide Z-Phe-His-Leu-NHj (Z = carboben-zyloxy). This compound has been shown before in the literature to display catalytic properties towards the hydrolysis of certain esters. The authors were particularly interested in the stereoselectivity of the process of L- towards D-amino acids and less in the enhancement of catalysis operated by the micelles. The substrate chosen was a very lipophylic ester, nitrophenylpalmitate. Morigaki used oleate vesicles, and later POPC liposomes, obtaining qualitatively similar results. ... 

Cuenya, B. R., Hyeon Baeck, S., Jaramillo, T. F., and McFarland, E. W. (2003) Size-and support-dependent electronic and catalytic properties of Au°/Au3+ nanoparticles synthesized from block copolymer micelles. J.Am. Chem. Soc., 125, 12928-12934... 

P-13 - Catalytic properties of micelle templated microporous and mesoporous materials for the conversion of low-density polyethylene... 

Along with monometalUc Pd nanoparticles, we studied the synthesis and properties of PdAu, PdPt, and PdZn bimetallic nanoparticles prepared at a molar ratio of 4/1 in PS-b-P4VP micelles and their catalytic behavior in DHL hydrogenation [44]. Because the amount of Pd in all the bimetallic nanoparticles is much higher than that of the second metal, Pd mainly determines the catalytic properties. 

Since the micellar characteristics of the PEO-b-P2VP-Pd block copolymer aggregates in a given solvent and at a given pH may influence the catalytic properties, this was another important variable for the present system. PEO-fe-P2VP forms micelles in water whose characteristics are mainly preserved after metallation (incorporation of a metal salt and metal nanoparticle formation) [49], but the behavior of this system in the presence of isopropanol is more complicated. To clarify the effect of solvent composition and pH on micellar characteristics, TEM and atomic force microscopy (AFM) studies of the key reaction mixtures were performed. Table 3.2 summarizes the catalytic data and mean diameters of the micelles and micellar aggregates obtained from AEM. 

Thus, micelle characteristics depending on pH and IPrOH water ratio play a crucial part in the catalytic properties as they may control the substrate and product transport towards active centers and their modification. 

L. Ya. Zakharova, F. G. Valeeva, L. A. Kudryavtseva, Yu. F. Zuev, Micelle forming properties and catalytic effect of the system sodium dodecyl sulfate-ethylene glycol in solvolysis of p-nitrophenyl bis(chloromethyl)phosphinate, Russ. J. Gen. Chem., 2002, 72, 1367-1372. 

Egorova E. M., Revina A. A., Rostovshchikova T. N. Bactericidal and Catalytic Properties of Stable Metallic Nanoparticles in the Reverse Micelles, VestnikMoskovskogo Universitieta Sen 2. Khimiya 2001, v. 42, Jf 5, 332-338 (in Russian). 

DBCH to cyclohexene in microemulsions was achieved with turnover numbers much higher than with dissolved catalysts. The catalytic properties of these PLL-Co films could be controlled by microemulsion composition [61 ], and anionic micelles formed within the cationic films in SDS microemulsions. 

Eryomin, A.N., Metelitza, D.I. 1999. Effect of hydration degree of aerosolOT reversed micelles and surfactant concentration in heptane on spectral and catalytic properties of catalase. Biochemistry Moscow) 64, 1049-1060. 

It turned out that the dodecylsulfate surfactants Co(DS)i Ni(DS)2, Cu(DS)2 and Zn(DS)2 containing catalytically active counterions are extremely potent catalysts for the Diels-Alder reaction between 5.1 and 5.2 (see Scheme 5.1). The physical properties of these micelles have been described in the literature and a small number of catalytic studies have been reported. The influence of Cu(DS)2 micelles on the kinetics of quenching of a photoexcited species has been investigated. Interestingly, Kobayashi recently employed surfactants in scandium triflate catalysed aldol reactions". Robinson et al. have demonshuted that the interaction between metal ions and ligand at the surface of dodecylsulfate micelles can be extremely efficient. ... 

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